The invention concerns an audio system for vehicles, in particular for motor vehicles, comprising a device component permanently fixed to the vehicle and a mobile component connected to it in a mechanically detachable way, as well as a control unit arranged in the permanently fixed device component, by means of which the function of the audio system is interrupted when the mobile component is removed, and resumed, following an authorization check, when the mobile component is put back in its place, whereby for the authorization check the control device contains a comparator unit for comparing the numerical code stored in the mobile component with the security code stored in the stationary device component.
In order to protect audio systems, for example car radios, car telephones and similar devices designed for mobile use, it is known to connect the mobile component in an electrically and mechanically detachable way with the device component installed in the vehicle. When the user leaves the vehicle and undoes the mobile component, the function is interrupted. If subsequently, the authorized user puts the mobile component back in its intended place into the permanently fixed device component, whereby the respective mechanical contacts establish the electrical connection between the mobile component and the permanently fixed housing component, the function of the audio system is released. As a rule, release is after a check to verify whether the inserted mobile component is that of the authorized user. With known devices, for example, integrated circuits are used in the mobile component, which integrated circuits are supplied with the necessary operating voltage by way of connecting terminals, and whose input- and output connections are also connected to the permanently-fixed device component by way of these connecting terminals. Such a connection often causes contact problems which lead to faulty behavior, for example resulting in the function of the audio system not being released again, even for the authorized user.
An audio system of the type mentioned above is known from U.S. Pat. No. 5,349,326.
From this, an audio system is known in which its device component permanently fixed to the vehicle comprises a memory consisting of an EEPROM. The front panel, removably connected to it, comprises an operating field 9 as well as a memory 10 used to store a secret code. In addition, a read-out control device 11 for reading our the secret code from the memory 10 is required. Memory 10 also comprises and EEPROM, located in the permanently fixed device component, as is the memory.
In order to transmit the secret code from the mobile component to the permanently fixed device component, expensive electronics comprising the blocks 9, 10, and 11 are necessary.